<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .wrap {
            display: flex;
            width: 400px;
            height: 400px;
            border: 1px solid;

            /*决定主轴是哪一根 以及 主轴的方向*/
            /*决定侧轴是哪一根 以及 侧轴的方向*/
            /*flex-direction: row;
            flex-wrap: wrap-reverse;*/
            /* flex-flow: row nowrap; */

            /*主轴的富裕空间管理*/
            /* justify-content: space-between; */
            /*侧轴的富裕空间管理*/
            /* align-items: flex-end; */
            /* align-content: flex-start; */
        }

        .item {
            width: 50px;
            height: 50px;
            background: pink;
            font-size: 13px;
            line-height: 50px;
            text-align: center;
            border: 1px solid;
            box-sizing: border-box;

            flex-grow: 1;
        }

        .wrap .item:nth-child(3) {
            /* align-self: center; */
            /* order: -1; */
        }
    </style>
</head>

<body>
    <div class="wrap">
        <div class="item">1</div>
        <div class="item">2</div>
        <div class="item">3</div>
        <div class="item">4</div>
        <div class="item">5</div>
        <div class="item">6</div>
    </div>
</body>

</html>